Composition of matter and method



Patented Feb. 18, 1936 UNITED STATES COMPOSITION OF MATTER AND METHOD OFITS PRODUCTION Cari G. Dreymann, Pittsburgh, Pa., assignor to GrantPaper Box Company, a corporation of Pennsylvania No Drawing. ApplicationMay 17, 1934, Serial No. 726,110

5 Claims.

This invention consists in a composition of matter having adhesive andwater-proofing properties, and in the method of its production. This newcomposition is useful in sheeted form, particularly in the packaging ofgoods for the market. The composition of matter may be prepared and soldin bulk, to be applied by the purchaser as an adhesive for uniting pliesof paper,

or for uniting a sheet of metal foil to a ply of paper; or to be appliedas a surface coating of moisture-proof character upon a supporting sheetof paper, card-board, or other material.

A sheet or film formed of the composition of matter of my invention andconstituting a component part of the wall of a container for thepackaging of material prevents ingress of atmospheric moisture topackaged material such in nature as to suffer damage or deterioration bysuch ingress (as, for instancabreakfast food); similarly such a sheet orfilm so applied will be effective in preserving moist packaged material(such as cake, for example) from deterioration in consequence of escapeof moisture.

The impervious film or sheet will ordinarily be spread upon a sheet ofrelatively rigid fibrous material, as, for example, a sheet of paper orcardboard (of which latter material the cartons and containers of suchfood substances as I have mentioned are commonly formed); and, since thematerial of which the impervious sheet is formed is suitable andadequate to such end, I preferably employ it as the adhesive, unitinglayers or plies of fibrous material built up for the purpose in view.Accordingly, the invention finds utility in the form of a sheet or filmof impervious material spread upon and integrated with a sheet offibrous material; and, yet more specifically, in the form of a sheet offilm of impervious material spread upon and between and efiecting theunion of two sheets or plies of fibrous material.

Moisture-proof paper, as a rule, is made by impregnating or coatingpaper with paraffin. In some instances parafiin is used as an adhesiveto unite two sheets or plies of paper; but for most purposes theadhesive afforded by paraffin is not strong enough. Still less suitableis paraflin for uniting layers of cardboard. I

I have found that amorphous, substantially saturated compounds formedfrom high-boilingpoint, non-saturated petroleum derivates bypolymerization and possibly by condensation, and which are known aspetrolatum, have properties that, modified by certain additions, renderthem adequate, when extended to the form of sheet or film, not only towithstand penetration by moisture, but also to adhere to sheets offibrous material upon which they may be extended, and to unite sheets ofsuch material between which they may be spread and incorporated.,Lately,

resin) higher melting substances have been separated from petrolatum andmineral oil and are sold as wax, to distinguish them from other,crystalline, saturated hydrocarbons, sold as parafiln. Themelting-points of these substances vary from to F. But while theiradhesive power is greater than that of the crystalline paraffins, stillthey are not always adequate as intercalated films, uniting layers orplies of cardboard. By a systematical investigation I have found thatthere exists a relationship between the adhesive power of organiccompounds and their viscosity at elevated temperature; and, as a result,I have succeeded in elaborating means by which I not only have been ableto increase the viscosity and adhesive power of these compounds, butalso to increase their plasticity. This invention, accordingly,embraces, first, a material to be used as the basis of a compound, whichshall have adhesive properties, and which, when extended in the form ofa sheet or film shall resist the passage of moisture-laden air. Thismaterial preferably consists of amorphous, substantially saturatedcompounds that have been formed from high boiling-point, non-saturatedpetroleum 'derivatives by way of polymerization and possibly bycondensation (which products in the raw state are known commercially aspetrolatum); and, more specifically, those higher melting substancesseparated therefrom and sold as petroleum wax. The invention, further,embraces a procedure in consequence of which the adhesive power andplasticity of these amorphous, substantially saturated compounds isincreased. Such procedure consists in dissolving a lesser or greateramount of a substance that, on cooling to about the temperature at whichthe coating is applied, or just before solidification, forms in thecompound a colloidal suspension or gel. I shall use the term colloidalsuspension as inclusive of a gel.

These colloidal suspensions or gels may be produced by adding to thebase material certain substances, which at low temperature are not atall or only partly soluble in the base material, but which can berendered soluble either by increasing the temperature, or by adding alsoan inter.- mediary substance in which both the base material and thegel-forming substance are soluble.

As substances which will form colloidal suspensions or gels I maymention: metal stearates, natural and artificial resins (such ascoumarone modified phenol-formaldehyde resins, glycol-phthalic acidresins, and other condensation and polymerization products on themarket,as also copal and other gums, and so on. Among these coumarone resin,phenol-formaldehyde resin, and copal gum are best; and of these three Ihave found coumarone resin very satisfactory. In using coumarone resin asolvent should also be employed, and a suitable (and non-volatile)solvent is ester gum. I

There are other intermediary substances, solvents both of the basematerial and of the added substance, that may be employed: for example,rosin.

The efiect that is brought about when colloidal suspensions or gels areformed in-such base material as has been specified is best illustratedby giving the viscosity determination, made with the Saybold universalviscosimeter at 210 expressed in seconds, of a number of specificsubstances.

The adhesive quality of substances 1 and 2 is practically nil; substance3 sticks better. Substances 4, 5 and 6 are adequate for my purposes; andof them it is to be remarked that adhesiveness increases at about equalrate with viscosity.

In typical performance of the invention, 1% of aluminum stearate isdissolved in amorphous petroleum wax heated to a temperature of 220 F.

A clear solution results, which gelatinizes on cooln Again, parts ofpetroleum wax and 15 parts of ester gum are heated to 200 F. and tothem, when so heated and rendered fluid, 10 .parts of coumarone resinare added. The temperature is then gradually raised to 285 F. and keptthere until all solids have disappeared. The coumarone resin is nowpresent in saturated solution and, when the solution is slightly cooled,the resin either separates as a colloidal suspension, or forms a gel.Such a condition is indicated in the high viscosity figure of given inthe foregoing table. As compared with the base ma terial alone, the soprepared material is superior, both in adhesive quality and inplasticity. After the compound has been cooled to about 240 F.,

it is spread to the form of sheet or film, either upon a sheet'of paperor other fibrous material, or as the intercalated bond between plies ofcardboard. For plying purposes I preferably use the apparatus and methoddescribed in my co-pend ing application'Serial No. 693,110, filedOctober 11, 1933. In operating such machinery, the compound beingmaintained at the temperature stated, the webs of paper may be caused totravel at a speed of to 200 feet a minute.

Instead of forming the colloidal suspension or gel within the substanceof the base material, it may be formed separately and afterward stirredin. I

The base material that I employ has a melting-point that ranges, as Ihave said, from 120 to 170 F. By making selection in this matter ofmelting-point of the base material, and by varying the ratio of theadded coumarone resin (or its equivalent) it is possible to attain inthe finished compound a melting-point that ranges from 140 to 190 F. Andwithin this range choice will be exercised and the procedure adapted,according to season (whether for summer or winter use), or according tothe climate of the country to-which the packaged, goods are to beshipped.

The petroleum wax base may be modified by dilution with parafiin, and bysuch modification the cost may be diminished. The degree to which suchdilution may be carried is in one aspect of the matter unlimited: thatis to say, parafiin may take 'the place of petroleum wax, even tocomplete displacement (100%) and still the colloidal suspension that isthe essential feature of the invention may be effected, and with thegood result that I have discovered,namely, that of increasing thewater-proofness or moistureresisting property of the material. While itis true that paraflin alone might serve as a base for carrying thecolloidal suspension, and with advantage, in that paper coated with itwould be found to be superior in its moisture-proofness to paper coatedwith paraflin that carries no colloid, still the paper would be found tobe like ordinary parafiin paper, in that the coating would crack readilyat folds. It is, therefore, requisite for the ends in view that in thebase material petroleum wax shall be present to the amount of at least20%. Petroleum wax, present in the base as a fractional ingredient, oras itself constituting the single component, is requisite both in thatits water-proof character is superior to that of parafiin; and in thatit is plastic, whereas paraflin is brittle. A base that includes 20% ofpetroleum wax and upward will be found to be satisfactory, even wherethe coated paper is to be folded and creased.

I claim as my invention:

1. A container wall for the packaging of material including a sheet orfilm composed substantially of amorphous petroleum wax of an apparentmelting-point of 120-170 F., carrying a parent melting-point of 120-170F., carrying a suspended colloid, and two sheets of fibrous material,the sheet or film of said wax intercalated between the sheets of fibrousmaterial and constituting a film of adhesive uniting the whole.

4. A container wall for the packaging of material including a sheet orfilm composed substantially of amorphous petroleum wax of an apparentmelting-point of. 120-170 F., carrying a resin in the condition ofcolloidal suspension.

5. A container wall for the packaging of material including a sheet orfilm composed substantially of a mixture of amorphous petroleum wax ofan apparent melting-point of 120-170 F. and ester gum, carrying incolloidal suspension a resin.

CARL G. DREYMANN.

